At first, books were kept in chests but as they became published in bulk they moved into the cupboard. The doors came off and the bookcase began to evolve. Today, bookcases can be integral architectural elements that shape space and, in some cases, even light. In celebration of International Day of the Book on April 23rd, ArchDaily compiled this round-up of architecturally, innovative bookcases.

Of all construction materials, concrete is perhaps the one that allows the greatest diversity of finishes and textures. The mixture of its ingredients, the shape and texture of the formwork, and the pigmentation of the materials all offer the opportunity to achieve an interesting design. This week we've prepared a selection of 10 inspiring images of innovative concrete, taken by renowned photographers such as Gonzalo Viramonte, Song Yousub, and Ana Cecilia Garza Villarreal.

New technological developments in construction have given architects great freedom when designing. Innovations in construction materials and their properties allow for the creation of increasingly original and surprising facades. The buildings constructed as a result can even inspire people to travel thousands of kilometers just to see these masterpieces. This week, we present 15 of most ground-breaking facades through photos by prominent photographers such as Paul Ott, Peter Bennetts and Laurian Ghinitoiu.